diff --git a/Meadowlark-js/backends/meadowlark-mongodb-backend/test/integration/locking/Update.test.ts b/Meadowlark-js/backends/meadowlark-mongodb-backend/test/integration/locking/Update.test.ts
new file mode 100644
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+++ b/Meadowlark-js/backends/meadowlark-mongodb-backend/test/integration/locking/Update.test.ts
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: Apache-2.0
+// Licensed to the Ed-Fi Alliance under one or more agreements.
+// The Ed-Fi Alliance licenses this file to you under the Apache License, Version 2.0.
+// See the LICENSE and NOTICES files in the project root for more information.
+
+import {
+  DocumentInfo,
+  newDocumentInfo,
+  newSecurity,
+  meadowlarkIdForDocumentIdentity,
+  DocumentReference,
+  UpsertRequest,
+  NoResourceInfo,
+  ResourceInfo,
+  newResourceInfo,
+  DocumentUuid,
+  TraceId,
+} from '@edfi/meadowlark-core';
+import { ClientSession, Collection, MongoClient } from 'mongodb';
+import { MeadowlarkDocument, meadowlarkDocumentFrom } from '../../../src/model/MeadowlarkDocument';
+import {
+  asUpsert,
+  getConcurrencyCollection,
+  getDocumentCollection,
+  getNewClient,
+  onlyReturnId,
+  insertMeadowlarkIdOnConcurrencyCollection,
+} from '../../../src/repository/Db';
+import {
+  validateReferences,
+  onlyReturnAliasIds,
+  onlyDocumentsReferencing,
+} from '../../../src/repository/ReferenceValidation';
+import { upsertDocument } from '../../../src/repository/Upsert';
+import { setupConfigForIntegration } from '../Config';
+import { ConcurrencyDocument } from '../../../src/model/ConcurrencyDocument';
+
+jest.setTimeout(120_000);
+
+const documentUuid = '2edb604f-eab0-412c-a242-508d6529214d' as DocumentUuid;
+
+// A bunch of setup stuff
+const edfiSchoolDoc = {
+  schoolId: 123,
+  nameOfInstitution: 'A School 123',
+  educationOrganizationCategories: [
+    {
+      educationOrganizationCategoryDescriptor: 'uri://ed-fi.org/EducationOrganizationCategoryDescriptor#Other',
+    },
+  ],
+  schoolCategories: [
+    {
+      schoolCategoryDescriptor: 'uri://ed-fi.org/SchoolCategoryDescriptor#All Levels',
+    },
+  ],
+  gradeLevels: [
+    {
+      gradeLevelDescriptor: 'uri://ed-fi.org/GradeLevelDescriptor#First Grade',
+    },
+  ],
+};
+
+const schoolResourceInfo: ResourceInfo = {
+  ...newResourceInfo(),
+  resourceName: 'School',
+};
+
+const schoolDocumentInfo: DocumentInfo = {
+  ...newDocumentInfo(),
+  documentIdentity: { schoolId: '123' },
+};
+
+const schoolMeadowlarkId = meadowlarkIdForDocumentIdentity(schoolResourceInfo, schoolDocumentInfo.documentIdentity);
+
+const newUpsertRequest = (): UpsertRequest => ({
+  meadowlarkId: schoolMeadowlarkId,
+  resourceInfo: NoResourceInfo,
+  documentInfo: schoolDocumentInfo,
+  edfiDoc: edfiSchoolDoc,
+  validateDocumentReferencesExist: false,
+  security: { ...newSecurity() },
+  traceId: 'traceId' as TraceId,
+});
+
+const referenceToSchool: DocumentReference = {
+  projectName: schoolResourceInfo.projectName,
+  resourceName: schoolResourceInfo.resourceName,
+  documentIdentity: schoolDocumentInfo.documentIdentity,
+  isDescriptor: false,
+};
+
+const schoolDocument: MeadowlarkDocument = meadowlarkDocumentFrom({
+  resourceInfo: schoolResourceInfo,
+  documentInfo: schoolDocumentInfo,
+  documentUuid,
+  meadowlarkId: schoolMeadowlarkId,
+  edfiDoc: edfiSchoolDoc,
+  validate: true,
+  createdBy: '',
+  createdAt: Date.now(),
+  lastModifiedAt: Date.now(),
+});
+
+const academicWeekResourceInfo: ResourceInfo = {
+  ...newResourceInfo(),
+  resourceName: 'AcademicWeek',
+};
+const academicWeekDocumentInfo: DocumentInfo = {
+  ...newDocumentInfo(),
+  documentIdentity: {
+    schoolId: '123',
+    weekIdentifier: '123456',
+  },
+
+  documentReferences: [referenceToSchool],
+};
+const academicWeekMeadowlarkId = meadowlarkIdForDocumentIdentity(
+  academicWeekResourceInfo,
+  academicWeekDocumentInfo.documentIdentity,
+);
+
+const academicWeekDocument: MeadowlarkDocument = meadowlarkDocumentFrom({
+  resourceInfo: academicWeekResourceInfo,
+  documentInfo: academicWeekDocumentInfo,
+  documentUuid,
+  meadowlarkId: academicWeekMeadowlarkId,
+  edfiDoc: {},
+  validate: true,
+  createdBy: '',
+  createdAt: Date.now(),
+  lastModifiedAt: Date.now(),
+});
+
+describe('given an upsert (update) concurrent with an insert referencing the to-be-updated document - using materialized conflict approach', () => {
+  let client: MongoClient;
+
+  beforeAll(async () => {
+    await setupConfigForIntegration();
+
+    client = (await getNewClient()) as MongoClient;
+    const mongoDocumentCollection: Collection<MeadowlarkDocument> = getDocumentCollection(client);
+    const mongoConcurrencyCollection: Collection<ConcurrencyDocument> = getConcurrencyCollection(client);
+
+    // Insert a School document - it will be referenced by an AcademicWeek document while being updated
+    await upsertDocument({ ...newUpsertRequest() }, client);
+
+    // ----
+    // Start transaction to insert an AcademicWeek - it references the School which will interfere with the School update
+    // ----
+    const upsertSession: ClientSession = client.startSession();
+    upsertSession.startTransaction();
+
+    // Check for reference validation failures on AcademicWeek document - School is still there
+    const upsertFailures = await validateReferences(
+      academicWeekDocumentInfo.documentReferences,
+      [],
+      mongoDocumentCollection,
+      upsertSession,
+      '',
+    );
+
+    // Should be no reference validation failures for AcademicWeek document
+    expect(upsertFailures).toHaveLength(0);
+
+    // ***** Read-for-write lock the validated referenced documents in the insert
+    // see https://www.mongodb.com/blog/post/how-to-select--for-update-inside-mongodb-transactions
+    // await writeLockReferencedDocuments(mongoDocumentCollection, academicWeekDocument.outboundRefs, upsertSession);
+
+    // ----
+    // Start transaction to update the School document - interferes with the AcademicWeek insert referencing the School
+    // ----
+    const updateSession: ClientSession = client.startSession();
+    updateSession.startTransaction();
+
+    // Get the aliasMeadowlarkIds for the School document, used to check for references to it as School or as EducationOrganization
+    const udpateCandidate: any = await mongoDocumentCollection.findOne(
+      { _id: schoolMeadowlarkId },
+      onlyReturnAliasIds(updateSession),
+    );
+
+    // Check for any references to the School document
+    const anyReferences = await mongoDocumentCollection.findOne(
+      onlyDocumentsReferencing(udpateCandidate.aliasMeadowlarkIds),
+      onlyReturnId(updateSession),
+    );
+
+    // Update transaction sees no references yet, though we are about to add one
+    expect(anyReferences).toBeNull();
+
+    // Perform the insert of AcademicWeek document, adding a reference to to to-be-updated document
+    const { upsertedCount } = await mongoDocumentCollection.replaceOne(
+      { _id: academicWeekMeadowlarkId },
+      academicWeekDocument,
+      asUpsert(upsertSession),
+    );
+
+    // **** The insert of AcademicWeek document should have been successful
+    expect(upsertedCount).toBe(1);
+
+    // RND-644
+    // Adds the academic week and the, to be updated, school to the concurrency collection.
+    const concurrencyDocumentsAcademicWeek: ConcurrencyDocument[] = [];
+    concurrencyDocumentsAcademicWeek.push({ meadowlarkId: academicWeekMeadowlarkId, documentUuid });
+    concurrencyDocumentsAcademicWeek.push({ meadowlarkId: schoolMeadowlarkId, documentUuid: schoolDocument.documentUuid });
+
+    await insertMeadowlarkIdOnConcurrencyCollection(mongoConcurrencyCollection, concurrencyDocumentsAcademicWeek);
+
+    // ----
+    // End transaction to insert the AcademicWeek document
+    // ----
+    await upsertSession.commitTransaction();
+
+    // RND-644
+    const concurrencyDocumentsSchool: ConcurrencyDocument[] = [];
+    concurrencyDocumentsSchool.push({
+      meadowlarkId: schoolMeadowlarkId,
+      documentUuid: schoolDocument.documentUuid,
+    });
+
+    // Try updating the School document - should fail thanks to the conflict in concurrency collection
+    try {
+      await insertMeadowlarkIdOnConcurrencyCollection(mongoConcurrencyCollection, concurrencyDocumentsSchool);
+
+      schoolDocument.edfiDoc.nameOfInstitution = 'A School 124';
+
+      await mongoDocumentCollection.replaceOne({ _id: schoolMeadowlarkId }, schoolDocument, asUpsert(updateSession));
+      await updateSession.commitTransaction();
+    } catch (e) {
+      expect(e).toMatchInlineSnapshot(
+        `[MongoBulkWriteError: E11000 duplicate key error collection: meadowlark.concurrency index: meadowlarkId_1_documentUuid_1 dup key: { meadowlarkId: "Qw5FvPdKxAXWnGght_4HOBmlPt_xB_pA20fKyQ", documentUuid: "2edb604f-eab0-412c-a242-508d6529214d" }]`,
+      );
+    } finally {
+      // ----
+      // End transaction to update the School document
+      // ----
+      await updateSession.abortTransaction();
+    }
+  });
+
+  it('should still have the initial nameOfInstitution: A School 123', async () => {
+    const collection: Collection<MeadowlarkDocument> = getDocumentCollection(client);
+    const result: any = await collection.findOne({ _id: schoolMeadowlarkId });
+    expect(result.documentIdentity.schoolId).toBe('123');
+    expect(result.edfiDoc.nameOfInstitution).toBe('A School 123');
+  });
+
+  afterAll(async () => {
+    await getDocumentCollection(client).deleteMany({});
+    await getConcurrencyCollection(client).deleteMany({});
+    await client.close();
+  });
+});